Insomnia Can Worsen Chronic Pain Conditions

Below:

Next story in Science

People who have problems sleeping may also be more sensitive to
pain, thus potentially worsening the effects of chronic pain
conditions, new research from Norway shows.

In the study, researchers measured pain sensitivity in more than
10,000 adults who were participants in the Tromsø Study,
anongoing public health study in Norway that began in 1974.

The results of the study showed that people
who had insomnia were more sensitive to pain than people who
didn't have sleep problems. In particular, people who were
experiencing chronic pain and who also had insomnia showed a
greater increased sensitivity to pain. Pain sensitivity was also
linked to the amount of time it took to get to sleep.

The findings show that "the need to improve sleep among
chronic pain patients, and vice versa, is evident," the study
authors, led by Børge Sivertsen of the Norwegian Institute of
Public Health in Bergen, Norway, wrote in their article.

In the study, the researchers first asked questions of the
participants about their experience with insomnia, how long it
took them to fall asleep and other sleep issues. For example,
participants rated their experiences with insomnia during the
previous year on a four-point scale, ranging from "never" to
"more than once a week." Out of all of the participants, 10.5
percent had what the researchers considered an insomnia disorder.
[ 7
Strange Facts About Insomnia ]

The participants then completed the cold-pressor test — a
standard
method used to mimic chronic pain in which people are asked
to place their hands in cold water for a set period of time.
People who remove their hands early show a decreased tolerance to
pain. In this study, the participants were asked to keep their
hands in water at 3 degrees Celsius (37 degrees Fahrenheit) for
106 seconds.

The results showed that 42 percent of patients who had insomnia
took their hands out of the water before the 106 seconds were up,
whereas only 31 percent of all of the participants did so. This
increased sensitivity to pain was greater in those with more
severe or more
frequent insomnia. For example, people who had insomnia once
a week were 52 percent more likely to take their hands out of the
water early, compared to those without insomnia. Moreover,
patients who had insomnia monthly were 24 percent more likely to
take their hands out of the water early.

The total amount of time that people spent sleeping showed no
effect on their pain tolerance, according to the study.

The link between sleep problems and chronic pain appeared
especially pronounced, according to the study. The patients with
both severe insomnia and chronic pain were more than twice as
likely to take their hands out of the water earlyas participants
who had neither condition. This effect was "synergistic," meaning
the two conditions combined had a greater effect than one would
expect from just summing their individual effects, the study
authors reported.

That synergy between chronic pain and sleep disorders suggests
health care providers should consider jointly treating the two
conditions in some patients, the authors stated. Both
cognitive-behavioral therapy and medications are used to treat
the two conditions separately, the authors noted, so further
studies should look at using these methods to treat the
conditions together.

Future research should look into not only clinical implications,
but also the role of neurotransmitters in the co-occurrence of
sleep disorders and pain, the authors said.